The inventors of this application have previously proposed a vane-type rotary compressor provided with a rotary sleeve interposed between a center housing and a rotor, under Japanese Patent Application No. 56-162025 (JP, A, 58-65988). The compressor is particularly suitable for use with an automobile engine required to operate over a wide speed range because of being substantially free from frictional heat as well as wear at the apex of each vane. However, there is the possibility of scuffing and seizure troubles if air is highly compressed in the compression working space within the compressor to push the rotary sleeve from within to the inner periphery of the center housing.
From a study on the movement of the rotary sleeve, it has been clarified that a contact between the rotary sleeve and the center housing takes place not at a specific line but in a relatively wide zone. The inventors have proposed under patent application No. 58-28608 (JP, A, 59-155589) that the air inlet is provided at the starting line of the zone in which the rotary sleeve is likely to contact and is internally connected to the open air, the discharge chamber, and the compression working space under the maximum pressure to increase an amount of air flowing over the zone. However, when a sudden change occurs in the rotational speed of the internal combustion engine, the rotor is driven to rotate. The rotary sleeve abnormally moves to contact the suction side inner periphery of the center housing, thereby rotating in a disorderly manner.
It is the primary object of the invention to provide an apparatus by which the rotary sleeve is floatingly supported without contacting the compression side inner periphery of the center housing when compressed air pushes the rotary sleeve from within to the compression side inner periphery and the suction side inner periphery when a sudden change occurs in the rotational speed of the rotor to move the rotary sleeve toward the suction side inner periphery.